Re: Debug build compile error in 'gobject/gobject.c'

This is likely a MSVC 8 issue. The GOBJECT_IF_DEBUG macro expands the
second argument to a code block, and it seems MSVC 8 has issues when
that includes a conditional pre-processor directive.
GOBJECT_IF_DEBUG hasn't changed since 2014, and the same commit
introduced the use you see failing.

That's what confused me. The last commit date for gobject.c seems to be
25th May 2014 and yet the same code section looked like this only a
fortnight ago:-